Woody's Workshop – Page 36 – Keeping the Grey Matter active

August 20, 2020

France visit with astro photography and Canon camera CHDK hack

Like all responsible citizens we have been in social distancing since March and throughout this time both my wife and I have been concerned about our house in France.

As infection rates seemed to be easing we decided to make a quick visit to the Dordogne to check all was well. Normally we take a ferry crossing but we really did not want to risk the exposure this would entail. Instead we opted to take the Channel Tunnel. For those not familiar with this route, you drive to the terminal, check in and then get loaded in your car onto a rail transport shuttle train. The journey through the Tunnel takes around 40 minutes and you off load near Calais in France and head south. This route offered minimal exposure to others as we were effectively in the car from door to door and not allowed to leave the vehicle on the shuttle train.

We live in the mid south of England so there was the discomfort of a 2 hour journey to the Folkestone to board the shuttle. Normally we have a 1 hour run to Portsmouth for the ferry. Once in France at Calais there was a 9+ hour run via Paris (not fun) down to the Dordogne. It was tiring but with the two of us taking shifts it eased the strain.

All was good at the house and we spent two weeks with minimal human contact and survived on the French ‘click and collect’ food supply services. We had some very high daily temperatures and some nice wine.

We have a very close friend called John living in France and he knows our house well and envies our Dark Sky location. He has similar interests in Fusion 360, horology, Arduino, mechanical design and relevant to this instance, astro-photography. August is the peak time for the Perseid meteor shower. We both own Canon Powershot SX50 HS zoom cameras and he made a comment that it was a shame that these did not have a Bulb setting for the shutter or the ability for us to do time lapse to take some shots of the meteor trails.

Investigating on the internet revealed that there is a group of enthusiasts that have hacked the operating system of the Canon range of cameras. This is known as CHDK (Canon Hack Development Kit). It allows you to load a firmware update into the camera to expand its capabilities but does not overwrite the default issued code. The CHDK code is wiped once you switch off and the camera reverts to normal.

CHDK provides facilities for long exposure times and for time lapse routines. This therefore addressed both the issues we had with the SX50. It took a while for us to share notes and to get our heads around how CHDK worked and how to set it up. I managed to get my camera hacked the day before it was time to journey home. I had one last night of hopefully cloud free viewing to get some images.

Those familiar with all things astro will know that a long exposure time image of the sky will be degraded by the movement of the Earth’s rotation. The result is ‘trails’ on the stars so they look elongated rather than single dots. John is developing an Arduino based star tracker but I did not have access to this but I did have my Celestron telescope. When the telescope is calibrated and locked it will keep track of the star movement and not leave trails.

I spent the day devising a mount for the Canon on the telescope and come 10 pm all was ready to run … except the cloud cover was really bad. I waited and waited and finally I got one run of 4 shots of 3 minutes each looking at the Milky Way. Given more time these could have been stacked in Registax or similar to enhance the images further.

Milky Way image taken with a Canon HS50 hacked with CHDK to give 3 minute exposures

I accept that the SX50 is far from ideal as an astro imaging camera. There is too much glass in the light path and the filtering and noise will be poor but this was a first step along the road. I was pretty pleased with the result. I now need to compare notes with John on his Arduino based star tracker. Another project to add to the ever increasing list …..

Next day we made the house secure and departed knowing that we now faced not just a 13 hour journey but also a 14 day quarantine period when we got home. But of course the upside is 14 days of uninterrupted workshop time.

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July 30, 2020April 23, 2023

3DConnexions Spacemouse joins the workshop

To date I have used Fusion 360 with just a mouse for screen manipulation. Over the past few months I seem to have developed Carpal Tunnel Syndrome in my right hand. (But there again it could just be old age taking its toll). This is painful at times but does depend on what activity I am undertaking. Some days just using a screwdriver can be taxing. I have begun wearing an elasticated wrist and thumb support which seems to have helped. While watching one of my many favourite Youtubers mention was made of the big improvement in 3D image manipulation that can be achieved with a 3D mouse. There is also some evidence that such a device does ease the strain on the wrist. It seems there is one major player in the market and that is 3DConnexion. I went through my previously published decision making process on a potential purchase and my Wireless Spacemouse arrived yesterday.

It is supplied with a soft storage pouch and there is a training course app with it which is straightforward. You can then play a quiz to see how good your hand / eye coordination is. Perhaps it is not good to dwell on the results of this …. Initially it is certainly weird to use but then it seems to click (?) with brain and muscle memory and then becomes a major step forward when using Fusion 360. You use your left hand on the Spacemouse and the right hand for normal mouse activity. I like it. In fact I like it a lot and wonder why I hadn’t latched onto it before now. Hopefully it will ease the strain on my right wrist and probably pass the burden to my left wrist …. arthritis rules. Similar or related subjects : –

July 11, 2020

3D Printed ESAB Warrior Tech Helmet Hinge Latch Plate

My TIG welding frustration suffered more than usual the other day .

I have an ESAB Warrior Tech helmet which works really well when welding but it would not stay flipped up when I wanted to see things in daylight. Every time I leaned forward the helmet would drop down over my eyes and thump me on the chest. Added to the fact I was trying to TIG some thin wall tubing I was no in no mood for distractions.

Before the helmet joined the happy hunting ground over the neighbours fence I took it apart to see why the latch up action was not working. Inspection revealed that the backing plate had cracked around the latching cam.

I could have bought a completely new head band assembly but the part in question might just be 3D printable. The Fusion 360 sketch ended up being very complicated based on eyeball guesses on curves and centres but on the second version I had a printed replacement which did the job …. for the time being anyway.

3D printed ESAB Warrior Tech latch plate replacement — The final version of the replacement plate for the ESAB Warrior Tech welding helmet latch.

If anyone is suffering from a bruised chest let me know and I will forward the Fusion file.

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July 10, 2020

After 3 years of waiting I have finally got bees in my hive

Bees Down the Garden

This is something way left field to my usual stuff.

Three years ago almost to the day my wife bought me a beehive for my birthday. This is not one of my normal activities and it was not a normal type of beehive. The design is marketed and I believe manufactured in the UK by Gardeners Beehive and you can see from the picture below it is very unconventional. It is meant to represent a hollow tree stump and is more in keeping with the natural home that bees would inhabit in the wild.

gardeners beehive — The unusual Gardener’s Beehive that has waited 3 years for some bees to arrive

The concept of the design is that once you have bees in residence you leave them alone. No white suits, smokers etc that are the norm for conventional hives. After the first year you can add honey boxes on the side of the hive. These act as additional storage for the bees over and above the bulk stored in the main section of the hive. Taking honey from these additional storage boxes does not drain the bees main store which they need to survive the winter. The hive does not deliver loads of honey in the way a conventional hive would but you get some busy pollinators buzzing round the garden.

So why has it taken three years to get bees in residence ? To be honest I don’t know. I followed all the instructions with the hive which detail the best location and the use of lure spray to attract the searcher bees but to no avail. Perhaps it was because swarms are most common in June, July and August when we would normally spend time in France so we missed the opportunities.

This year, isolated at home, we have spent more time in the garden and we have now seen three swarms pass overhead. It is quite an impressive sight if not a little intimidating. The third one took a fancy to a pear tree in our garden and this looked like a long awaited opportunity to get some residents.

There is a couple we know in the village who are beekeepers and we quickly rang them and asked for their help. They climbed into the tree and managed to shake most of the swarm into a cardboard box and then drop the buzzing contents into the top of my peculiar hive. It was then a matter of waiting to see if we had captured the queen and the swarm would like their new home.

Friendly local beekeepers transferring the swarm to my hive — Friendly local beekeepers transferring the swarm to my beehive

All seems well so far with lots of traffic to and from the hive so maybe the three year wait is finally over.

And if three swarms weren’t enough, next day I found a small one down in the vegetable plot clustered on one of the bed protection nets. It seems it is a good period for swarms.

Bee swarm in vegetable patch — Another smaller swarm the next day

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June 29, 2020June 30, 2020

Workshop resources all coming together like clockwork

Another JSN Job ?

You know how I keep on going on about how solutions to problems are often solved by coming at them from different and often unconventional directions, by utilising and marrying available resources ? It was a philosophy that I encouraged in my team while running my business and it has carried over into my way of working in retirement. A recent job brought his home to me.

A client had a very old clock that had had a new barrel wheel made and fitted but the clock would not run for more than a few minutes. There appeared to be an incompatibility either between the modulus of the new wheel and its mating pinion or the shape of the original pinion did not match the shape of the new wheel.

If you spun the barrel wheel you could feel the resistance build up as the synchronisation between the two profiles drifted out. Adding extra weight to the barrel helped but did not solve the problem.

So what to do ?

The barrel wheel was serious engineering and I did not fancy making a new one. The existing mating pinion was a seven leaf format and its leaves were what you might call pear drop shaped rather than the expected profile. The pinion arbor had a 72 tooth wheel driving the next part of the clock train but we did have a spare one of these to hand from the minute dial.

Calculations from the geometry of the barrel wheel resulted in a modulus figure of 1.86. A rather large value and not one that conventional cutters are readily available for. The pinion was perhaps something that could be drawn in Fusion 360 and then made on my Tormach CNC PCNC440 milling machine. The only snag was that the profile needed on the pinion would likely be weird and the world’s supply of brass could diminish rapidly while getting the profile correct.

Using Gearwheel Designer I created what would be the expected profile for a 7 leaf pinion with a modulus of 1.86. This was exported as a DXF line drawing into Fusion 360. This outline was extruded in Fusion into a 3D design and a boss was added to mount the 72 tooth wheel.

The design was 3D printed on my Sindoh 3DWOX printer and was mounted on a 6mm silver steel arbor. I added a driving disc that interlocked with the printed pinion and the crossings on the wheel to drive the assembly. Surprise surprise it didn’t run but it did mirror the regular pattern of stiffness of the original pinion.

The original arbor, pinion and wheel together with the driving disc and a 3D printed pinion test profile. The driving disc has screws to lock it to the wheel and two protruding pins to lock into the 3D printed pinion profile under test. The 3D printed profile was a tight pressure fit onto the new 6mm arbor.

I now had the test bed for quickly making and testing different pinion profiles. There followed a number of hours watching the engagement progression of the profile of the pinion into the barrel wheel and then trying to conceive a profile for the pinion that might run.

3D printed test profiles — Various trial profiles and the temporary driving disc to engage with the 72 tooth wheel

Test pinion in place on the new arbor — A test pinion in place showing the 72 tooth wheel and the driving disc

Fusion 360 made this process so easy and round 10 printed test profiles later I had success with a clock that now ran. The driving weight on the barrel was around 11kg and it looked to be worthwhile wasting some brass making a ‘proper’ one.

I took the 3D design and produced CAM code in Fusion. This would cut the profile ‘on end’ using an adaptive first cut with a 4mm end mill followed by rest machining the remaining material with a 2mm end mill.

Images of the Fusion 360 process of creating the new 7 leaf pinion — The Fusion 3D model of the pinion, the CAM simulation of the leaf cutting, first adaptive cut of the leaves and rest machining final pinion

The resulting brass pinion was mounted on the arbor and the clock ran with a strong beat. As expected the brass pinion gave less surface to surface resistance than the 3D printed part and the barrel driving weight was now able to be reduced down to 6.25kg.

new pinion mounted in the clock — The finished pinion mounted in the clock on the new arbor

I ran my Microset Timer on the clock overnight and had a first off timing error of 5 minutes per day which was fixable with a pendulum tweak. The movement had an instability of a few seconds per day which was quite astonishing.

The conclusion of the experience is that at first glance this seemed like a conventional pinion cutting exercise …. but M1.86 cutters are not readily available. If a cutter could have been found at less than a King’s Ransom it is likely that the resulting conventional profile would have been wrong to match the barrel wheel.

The alternative route that was taken of Gearwheel Designer to Fusion to 3D print to Fusion CAM to CNC machining solved the problem albeit with a final weird profile. The purists and traditionalists will groan. There will be a gnashing of teeth and a pulling out of hair.

Does it really matter if the result is new life for what could have become a heap of scrap metal ?

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